/Engine/Source/Runtime/CoreUObject/Public/UObject/UnrealTypePrivate.h
Used to safely check whether all of the passed in flags are set. This is required as PropertyFlags currently is a 64 bit data type and bool is a 32 bit data type so simply using PropertyFlags&CPF_MyFlagBiggerThanMaxInt won't work correctly when assigned directly to an bool.
true if all of the passed in flags are set (including no flags passed in), false otherwise
bool HasAllPropertyFlags ( uint64 FlagsToCheck ) const